In a volume production milieu where large numbers of cartons or cases traveling on a conveyor are filled and sealed in sequence, it is generally the practice to use a sealing tape head near the end of the conveyor to apply tape to the cartons to seal them. The tape head, under which the cartons pass, has a tape supply and payout, a roller to press the tape onto the carton, and means for cutting the tape at the end of the sealing operation. Usually the tape applying operation commences when the leading face of the carton strikes the roller, which has sealing tape on it. As the carton moves past the tape head, the roller is cammed up the leading face of the carton, rolls along the top face or surface thereof, and rolls down the trailing face, all the while applying tape and pressing it against the carton. The cutter cuts the tape usually after it has been applied to the upper portion of the trailing face. In order for the roller to apply sufficient pressure to the tape and carton to insure a proper seal, it is generally mounted on a pivot arm which is spring biased in such a manner that the roller bears firmly against the tape and carton throughout the sealing operation.
With such an arrangement sequential sealing of moving cartons is realized. However, inasmuch as the carton is moving away from the roller while the tape is being applied to the trailing face, the spring which biases the pivot arm must be strong enough for the roller to press and maintain the tape firmly against the carton as it moves away. On the other hand, as the leading face of a carton contacts the roller, if the same spring bias is too great the roller can, and often does, dent or break the material forming the leading face of the carton thereby risking damage to the contents or destroying the integrity of the carton. Also, as tape is applied to the top of the carton, which generally comprises two flaps forming a seam to be sealed, too great a pressure by the roller can cause a separation or collapse of the flaps, thereby widening the seam and resulting in a poor seal. Some of these problems can be, and often are, alleviated by markedly decreasing the speed of the conveyor, which tends to reduce damage to the leading face by lessening the impact of the roller therewith. However, in a volume production environment, a decrease in speed results in fewer sealed cartons per unit of time, which, on a cost basis, is undesirable.
Another solution is to use cardboard or other material for the cartons which is sturdy enough to withstand the pressures brought to bear on the leading face and the top of the carton. However, this often results in the necessary use of a heavier, stronger and, hence, more expensive material for the carton than is necessary to contain and protect the goods carried therein. Thus, again, from a cost basis, this solution is undesirable.